Axiom Of Choice

We have the following indirect implication of form equivalence classes:

147 \(\Rightarrow\) 137-k given by the following sequence of implications, with a reference to its direct proof:

Implication	Reference
147 \(\Rightarrow\) 91	The axiom of choice in topology, Brunner, N. 1983d, Notre Dame J. Formal Logic note-26
91 \(\Rightarrow\) 79	clear
79 \(\Rightarrow\) 139
139 \(\Rightarrow\) 137-k	Cancellation laws for surjective cardinals, Truss, J. K. 1984, Ann. Pure Appl. Logic

Here are the links and statements of the form equivalence classes referenced above:

Howard-Rubin Number	Statement
147:	\(A(D2)\): Every \(T_2\) topological space \((X,T)\) can be covered by a well ordered family of discrete sets.
91:	\(PW\): The power set of a well ordered set can be well ordered.
79:	\({\Bbb R}\) can be well ordered. Hilbert [1900], p 263.
139:	Using the discrete topology on 2, \(2^{\cal P(\omega)}\) is compact.
137-k:	Suppose \(k\in\omega-\{0\}\). If \(f\) is a 1-1 map from \(k\times X\) into \(k\times Y\) then there are partitions \(X = \bigcup_{i \le k} X_{i} \) and \(Y = \bigcup_{i \le k} Y_{i} \) of \(X\) and \(Y\) such that \(f\) maps \(\bigcup_{i \le k} (\{i\} \times X_{i})\) onto \(\bigcup_{i \le k} (\{i\} \times Y_{i})\).

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